1. Field of the Invention
The present invention relates generally to an improvement of a brush apparatus of a rotary electric machine such as motors and, more particularly, to an improvement in preventing a brush from coming off from a brush holder by wearing.
2. Related Art
The prior art brush apparatus is proposed in Japanese Utility Model Laid-open No. 5-60154. In the prior art, a pigtail (feeder) is assembled integrally beforehand to a side surface of a brush in a compressing direction thereof. A slit, is formed at the side surface in the compressing direction of a brush holder holding the brush. A front end portion in the compressing direction of the slit is shaped to open outward. Near the opening end portion of the slit, a stopper piece is formed integrally with a fixed clearance relative to the side surface of the brush holder. When the brush is held in the brush holder, by using a slack or a loose portion of the pigtail, the brush is inserted into the brush holder with the pigtail passing through the slit by avoiding the stopper piece.
The longer an operation period of the rotary electric machine becomes, the more the brush is worn away. Therefore, the brush and the pigtail are compressed by a spring and gradually move toward the opening end portion of the slit. After the pigtail moves near the opening end portion of the slit, the pigtail contacts the stopper piece so that the brush and the spring are prevented from coming off.
However, in the prior art apparatus mentioned above, when the brush is held in the brush holder, the brush is assembled by using the slack of the pigtail while avoiding the stopper piece. Thus, when the rotary electric machine works, loosening is produced in the pigtail and the brush cannot be prevented from coming off, reducing the reliability.
In order to reduce the slack of the pigtail, when the brush is inserted into the brush holder, avoiding the stopper piece may become difficult and productivity in brush insert work is decreased.